Zinc deficiency often key to immune decline, inflammatory disease

Since this deficiency is more the rule than the exception, and hard to measure, nutrition scientists at the Linus Pauling Institute recommend that all older adults take zinc.

A new study has described for the first time a biological mechanism by which zinc deficiency can develop with age, leading to:

• A decline of the immune system,

• And the increased inflammation associated with many health problems, including cancer, heart disease, autoimmune disease and diabetes.

The research - done at Oregon State University’s Linus Pauling Institute and College of Public Health & Human Sciences - suggests it is especially important for older people to get adequate dietary intake of zinc, since they may need more of this essential element as their ability to absorb it declines.

Though zinc is often underappreciated, it is very important for health, and second only to iron in concentration in the body. About 40% of older Americans and as many as two billion people around the world have diets that are deficient in this essential micronutrient, experts say.

Inflammatory Biomarkers Reduced with Zinc-Rich Diet

The research, published Oct 1 by the Journal of Nutritional Biochemistry,(1, 2) reflects studies in both animals and human cells.

Based on findings with laboratory animals, the OSU researchers found that zinc transporters were significantly dysregulated in old animals. Even though their diet supposedly contained adequate amounts of zinc:

• They showed signs of zinc deficiency,

• And had an elevated inflammatory response.

When the animals were given about 10 times a young animal’s dietary requirement for zinc, the biomarkers of inflammation were restored to those of young animals.

Poor Diet & Poor Absorption = DNA Damage, Inflammation

According to nutritional biologist Emily Ho, PhD, principal investigator of the study:

• “The elderly are the fastest growing population in the U.S. and are highly vulnerable to zinc deficiency. They don’t consume enough of this nutrient and don’t absorb it very well.

• “We’ve previously shown in both animal and human studies that zinc deficiency can cause DNA damage, and this new work shows how it can help lead to systemic inflammation.

• “Some inflammation is normal, a part of immune defense, wound healing and other functions. But in excess, it’s been associated with almost every degenerative disease you can think of, including cancer and heart disease. It appears to be a significant factor in the diseases that most people die from.”

Diet-wise, high protein is synonymous with higher amounts of zinc. Meats are good sources of zinc, and though it is also obtained from nuts, whole grains, and legumes, the zinc in these vegetable sources is not as bioavailable, so low-protein & vegetarian diets tend to be zinc-poor.

And as a result of the new research showing declining zinc absorption with age, says Dr. Ho, she would recommend that all aging adults take a dietary supplement that includes the full RDA for zinc (which is 11 milligrams a day for men and 8 milligrams for women).

• “This can cause an increase in DNA methylation and histone modifications that are related to disease processes, especially cancer.

• “Immune system cells are also particularly vulnerable to zinc deficiency.”

Drs. Ho and Wong go on to explain that research at OSU and elsewhere has shown:

• Zinc is essential to protect against oxidative stress and help repair DNA damage.

• In zinc deficiency - the risk of which has been shown to increase with age - the body’s ability to repair genetic damage may be decreasing,

• Even as the amount of damage is going up.

Zinc Testing Rare - and Generally Inconclusive

Medical tests to determine zinc deficiency are rarely done, the researchers explain - and are not particularly accurate even if they are done. So the best approach is to assure adequate intake of the nutrient through diet or supplements, especially in older adults.

And, as for a proper RDA for older adults, they note that the current recommendation is the same as for younger adults – suggesting the subject should be examined more closely.

On the other hand, say Drs. Ho and Wong, levels of zinc intake above 40 milligrams per day should be avoided, since at very high levels zinc can interfere with absorption of other necessary nutrients, including iron and copper

These studies were supported by the National Institutes of Health and other agencies.

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Source: Based on information in Oregon State University/Linus Pauling Institute news release, Oct 1, 2012. The Linus Pauling Institute at OSU is a world leader in the study of micronutrients and their role in promoting optimum health or preventing and treating disease. Major areas of research include heart disease, cancer, aging and neurodegenerative disease.